Precious metal in substrate such as mined ore can be recovered by contacting the substrate with leaching solution. Typically, the leaching solution is an aqueous-based solution. Generally, the leaching solution is contacted with substrate to solubilize the precious metal. Thereafter, valuable components of the solution, such as the solubilized precious metal, are recovered.
Issues with past approaches relate to: efficiency of leaching recovery; avoidance of undesirable materials such as cyanide materials; and generation of stable solutions. Improvements in at least one, and sometimes more, of these issues are sought.